1. Field of the Invention
Embodiments of the present invention relate, generally, to interfused nanocrystals and a method of preparing the same, and more particularly, to interfused nanocrystals comprising two or more materials, which further include a layer comprising an alloy of the above materials, and to a method of preparing the interfused nanocrystals.
2. Description of the Related Art
In general, nanocrystals, which are materials having nano meter sized crystals, are composed of hundreds to thousands of atoms. As such, since the small sized material has a large surface area per unit volume a large portion of the atoms is exposed on the surface of the material. Therefore, manifesting unique electrical, magnetic, optical, chemical, or mechanical properties, different from the inherent properties of the material itself, can be adjusted by controlling the physical size of the nanocrystals.
Conventionally methods of preparing nanocrystals in dry phase have been attempted using vapor deposition processes, such as MOCVD (Metal Organic Chemical Vapor Deposition) or MBE (Molecular Beam Epitaxy). Chemical wet processes to grow crystals by adding a precursor to an organic solvent in the presence of a surfactant has been rapidly developed over the latest ten years. In a chemical wet process, when the crystals are grown, the surfactant naturally surrounds the surface of the nanocrystals and thus functions as a dispersant to control the growth of the crystals. Therefore, a chemical wet process may be performed more easily and inexpensively than vapor deposition processes such as MOCVD or MBE, thus uniformly controlling the size and shape of the nanocrystals.
U.S. Pat. No. 6,322,901 discloses a semiconductor nanocrystal material having a core-shell structure and increased quantum efficiency, and U.S. Pat. No. 6,207,229 discloses a method of preparing a semiconductor nanocrystal material having a core-shell structure. The semiconductor nanocrystals having a core-shell structure are reported to have quantum efficiency increased to 30-50%. In the above-mentioned conventional techniques, the optical property of a nanocrystal emitting pure-wavelength light with high efficiency, which is induced by the electron-hole recombination only at an edge of an energy band gap, may be applied to displays or to bio image sensors.
However, the above conventional techniques are disadvantageous because the preparation of core-shell nanocrystals emitting blue light requires a core crystal having a small size (a diameter of 2 nm or less), which becomes very unstable during the shell growth reaction and thus may aggregate.